Intraoperative ketamine shows no long-term opioid-sparing signal after spine surgery

Design

Propensity-matched retrospective database cohort

Population

55,670 adults after lumbar spine surgery (53,639 opioid-naive, 2,031 with OUD)

Primary outcome

Outpatient opioid prescriptions from 48 hours to 12 months

Effect

Opioid-naive: RR 1.23 at 48 h, 1.14 at 6 weeks; no difference at 3 to 12 months

This propensity-matched analysis of the TriNetX database compared lumbar spine surgery patients who did or did not receive intraoperative ketamine between 2010 and 2024: 53,639 opioid-naive patients and 2,031 with opioid use disorder.

In opioid-naive patients, ketamine was associated with more outpatient opioid prescribing at 48 hours (RR 1.23, 1.22 to 1.25) and 6 weeks (RR 1.14, 1.10 to 1.18), and no difference at 3, 6 or 12 months. In patients with opioid use disorder, prescribing was higher only at 48 hours. Opioid-related adverse events and new opioid use disorder were similar or more frequent with ketamine.

Ketamine is often added on the premise that it reduces central sensitisation and later opioid use. This database found no population-level evidence of that. The higher early prescribing almost certainly reflects which patients were given ketamine — those expected to have worse pain — and the data have no dose information. It does not show ketamine is harmful, and randomised trials remain the better guide for acute pain.

• Do not rely on a single intraoperative ketamine dose to prevent chronic opioid use after spine surgery.
• Keep ketamine for its evidence-based role in acute pain and opioid-tolerant patients, within a multimodal plan.
• Plan opioid tapering and follow-up after spine surgery regardless of whether ketamine was given.
• Record ketamine dose and timing so future audits can test dose-dependent effects.

Why it matters

It questions a common assumption behind routine ketamine use in spine anaesthesia.

Don't overread it

Database study with no dose data and likely confounding by indication; it cannot show ketamine is ineffective or harmful.

The statistics, in plain English

A risk ratio of 1.23 means 23% more patients had an opioid prescription at 48 hours. With over 50,000 patients, the intervals are narrow, but precision does not remove the bias of who was chosen to receive ketamine.

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